use same black version on gh actions as locally

.github/workflows/black.yaml

@@ -1,4 +1,5 @@
 # https://black.readthedocs.io/en/stable/integrations/github_actions.html#usage
+# see also what we use locally, requirements.d/codestyle.txt - should be the same version here.
 
 name: Lint
 
@@ -9,4 +10,4 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - uses: psf/black@stable
+      - uses: psf/black@22.6.0